This page contains a Flash digital edition of a book.
in seven days directly from a sputum sample plus the determination of multi-drug resistance. However, the diagnostic test requires an inverted microscope, which is not a cheap piece of equipment and not many laboratories can afford it, especially not Peru’s ministry of health. The MODS reading also requires skilled technicians to interpret the patterns and correctly classify TB. Both of these reasons have meant it’s not been feasible to implement this equipment to any large degree in Peru, although this method is now being used in other countries including Singapore, Thailand, South Africa, Bangladesh, Ecuador and Bolivia. ‘We wanted to find a way of replacing a

costly microscope as well as the skilled technician to make the diagnosis,’ states Dr Zimic. In Peru, most newly-diagnosed patients are automatically put on a 10-month regime of first-line empirical drugs. If the patient doesn’t respond to the treatment, they are declared to have a multi-drug-resistant strain and put on a course of second-line drugs. During this time the patient remains ill and can transmit the disease.

to the problem: firstly, building an inexpensive digital microscope and secondly, developing a mathematical algorithm to automatically identify the Mycobacterium tuberculosis in a digital microscope image. The prototype microscope used optical components from Edmund Optics, including stages, lenses and a 45° mirror to deflect the light beam at 90°. The system was designed to be used for both manual readings

and to capture digital images of the slides, which can be sent for automated analysis at the UPCH-Bioinformatics laboratory servers with the algorithm. The algorithm takes 15 seconds to run on a standard PC and is 99.4 per cent sensitive and 99.7 per cent specific, according to Dr Zimic. ‘We proved that there was no significant

difference between results from our system and a $10,000 Nikon inverted microscope,’ Dr Zimic comments. After the seven-day culture period, the plate can be read under the microscope, the image from which is processed by the automated algorithm at the University servers to make the analysis. ‘The physician will know in seven days, with high accuracy, if the patient has TB

We hope the microscope will reduce diagnosis of drug-resistant TB in Peru from 10 months to seven days

Dr Zimic’s team took a two-pronged approach

and simultaneously if that patient is multi-drug resistant,’ he continues. ‘This test cuts out the 10-month empirical treatment of TB sufferers with first-line drugs by determining multi-drug- resistant strains initially, which means treatment can immediately commence with second-line drugs.’

The microscope can be built for as little as $400-500 using a simple dichroic lamp as the illumination source. Nikon or Olympus inverted microscopes cost from $8,000 upwards. The components from Edmund Optics were used to demonstrate the proof-of-concept system. ‘We bought different sets of lenses and stages from Edmund to design a microscope fit for this

04-01 Series Compact SLM DPSSLs

457, 473, 491, 515, 532, 561, 594 nm CW power up to 300 mW, rms<0.25%

05-01 Series

High power single frequency DPSSLs 355, 491, 532, 561, 660, 1064 nm CW power up to 2000 mW, rms <0.1%

MLD Series

Compact diode laser modules 405 - 660nm Fast and deep direct modulation Fully integrated control electronics

• Fluorescence imaging and analysis

• Raman spectroscopy • Interferometry

• Semiconductor metrology

HTCure™ manufacturing for ultra-robust lasers and ensured reliability!

Dr Mirko Zimic and his team at the Universidad Peruana Cayetano Heredia in Peru have developed a low-cost inverted microscope for diagnosing tuberculosis. Cobolt Headoffice, Sweden

Phone +46 8 545 912 30, E-mail

High Performance Lasers by Cobolt.

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44